dt-bindings: arm: samsung: document S3C6410-based boards binding

Add bindings for the FriendlyARM Mini6410 and Samsung SMDK6410 boards.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/arm/samsung/samsung-boards.yaml

···
               - samsung,smdk2416                # Samsung SMDK2416
           - const: samsung,s3c2416
 
+      - description: S3C6410 based boards
+        items:
+          - enum:
+              - friendlyarm,mini6410            # FriendlyARM Mini6410
+              - samsung,smdk6410                # Samsung SMDK6410
+          - const: samsung,s3c6410
+
       - description: S5PV210 based boards
         items:
           - enum: